1. Field of the Invention
The present invention generally relates to a method and apparatus for use within a screen printing type operation. In particular, the invention relates to a method and apparatus for tensioning and mounting a screen in separate directions on a dual frame system to be used in screen printing.
2. Description of the Related Art
Screen printing utilizes a tensioned screen or mesh mounted on a frame having a stenciled image thereon. Ink is applied through the screen in the areas where the stencil has not blocked the openings between the threads of the mesh. The screen/mesh is typically fixed onto a rectangular (sometimes square) frame. Screen/mesh printing is highly variable in nature, with one of the main causes being the tension variation across a screen/mesh simultaneously stretched in two directions, either immediately, or due to variable tension loss over time. The variation in tensioning forces also affects the regular nature of the woven screen/mesh structure, causing variation in screen/mesh opening sizes, and ink/fluid transfer rates. To address this systems are available for multi-stage screen/mesh stretching, to retension the screen/mesh after use, in an attempt to increase stability and consistency over time and use. However, these systems increase the cost of producing a stable and consistent screen printed product, and each time the screen/mesh is used it risks damage and loss. Screen/mesh is typically supplied on rolls for multiple applications and, to a very limited extent, pre-coated with stencil materials. The rolls are often large, difficult to handle, and liable to impact damage. Stretching systems for screen printing are highly variable in the range of mechanisms and techniques used.
A conventional screen/mesh stretching and mounting process is illustrated in FIGS. 1–4. A screen/mesh is initially clamped 10 and stretched 12 in two directions. A single frame is then moved 14 to contact the screen/mesh. The single frame is then fixed to the screen/mesh permanently or via retensionable side mechanisms 16. Excess screen/mesh is then trimmed and the screen/mesh is then ready for imaging and use 18. FIG. 2 illustrates effects 20 of two directional forces in a conventional screen/mesh stretching process. FIG. 3 illustrates effects 22 of two directional stretching in a conventional screen/mesh stretching process. FIG. 4 illustrates the usable area against waste area 24 of a screen/mesh in a conventional two directional stretching process.
Once the screen/mesh is attached to the single frame resistive forces to deflection are applied under a squeegee action in the plain of the screen/mesh. This is particularly true the nearer to the frame the squeegee travels. This results in variation in the squeegee deflection and screen/mesh contact across the width of the print image and perpendicular to the print direction. To address this squeegee action deflection forces are increased to ensure contact at the ends of the print area, which results in excess squeegee pressure and deflection at the center of the print image, causing increased squeegee wear, possible screen/mesh damage, and/or variation of ink and/or fluid transfer across the print width.
Once printing is complete, unless the screen/mesh is to be reused for the same print job, the stretched screen/mesh will be reclaimed by removal of the stencil material using harsh chemicals and/or high pressure water jets. This is a time consuming and costly process, only justified by the high screen/mesh preparation cost, and improved screen/mesh stability over time with the conventional single frame screen/mesh printing process. The screen/mesh reclamation is also potentially harmful to the environment, due to the need to use chemicals, water, and energy to remove the stencil, along with significant disposal issues for the remaining chemicals, stencil components, inks/fluids, and water remaining at the end of the process.
Therefore, a need exists for a method and apparatus for stretching and mounting a screen printing screen that assures reliable printing qualities, while offering the potential of a simplified production system by achieving disposable screen printing with woven screen/mesh materials.
The related art is represented by the following references of interest.
U.S. Patent Application Publication No. 2002/0061953 A1, published on Apr. 3, 2003 for Thomas R. Bruckl et al., describes a device for drawing a printing material web into a rotary printing press. The Bruckl et al. application does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 2,608,750, issued on Sep. 2, 1952 to Albert C. Cluzel, describes an apparatus for and a method of making printing screens. The Cluzel patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 2,759,217, issued on Aug. 21, 1956 to Albin K. Peterson, describes a stretching apparatus for forming thick sheets into thinner sheets. The Peterson patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 3,315,301, issued on Apr. 25, 1967 to Harold J. Dibblee et al., describes an apparatus for universally stretching and forming sheet material. The Dibblee et al. patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 3,361,612, issued on Jan. 2, 1968 to Francis W. Rowbottam, describes an apparatus for installing screening from a roll onto framing having marginal edges provided with a fusible material. The Rowbottam patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 4,186,660, issued on Feb. 5, 1980 to John W. Key, describes a screen printing frame with plastic side bars bondable to fabric by surface softening. The Key patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 4,430,815, issued on Feb. 14, 1984 to Stanley S. Wulc, describes a screen printing apparatus which includes a frame to which will be attached to the edge portions of a screen fabric. The Wulc patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 4,978,414, issued on Dec. 18, 1990, U.S. Pat. No. 5,096,524, issued on Mar. 17, 1992, Great Britain Patent Application Publication No. GB 2 171 053 A, published on Aug. 20, 1986, and Germany Patent Application Publication No. DE 3 601 167 A1, published on Dec. 18, 1990, for Yasuaki Ohtani et al., describe an automatic silk stretching apparatus for stretching silk on a silk screen printing frame. The Ohtani et al. '414 and '524 patents, the Great Britain '053 application, and the Germany '167 application do not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,063,842, issued on Nov. 12, 1991 to Joseph Clarke, describes a screen tensioning and framing device. The Clarke patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,136,797, issued on Aug. 11, 1992 to Greg A. Hildebrandt, describes a frame having shiftable bars with flexible ends for securing fabric using adhesive. The Hildebrandt patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,271,171, issued on Dec. 21, 1993 to David C. Smith, describes a stretching frame for a fabric material that provides for spring mounting of the four frame sides. The Smith patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,522,148, issued on Jun. 4, 1996 to Donald E. Newman, describes a registration/adapter apparatus for aligning a printing screen with an image platform. The Newman patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,581,918, issued on Dec. 10, 1996 to Christian Schilling et al., Germany Patent Application Publication No. DE 4 437 503 A1, published on May 4, 1995, and European Patent Application No. EP 0 650 832 A1, published on May 3, 1995, describe an apparatus for stretching out a rectangular material in a printing frame with tensioning devices which are arranged at the sides thereof. The Schilling et al. patent, the Germany '503 application, and the European '832 application do not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 5,598,776, issued on Feb. 4, 1997 to Slobodan Casl, describes a screen printing apparatus which is tensionable. The Casl patent does not suggest a method and apparatus for stretching and mounting a screen printing screen.
U.S. Pat. No. 5,937,751, issued on Aug. 17, 1999 to Eugene F. Newman, Jr., describes a screen printing frame and bordered fabric stretching devices for quickly stretching and for retensioning a screen. The Newman, Jr. '751 patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 6,070,526, issued on Jun. 6, 2000 to James D. Larson, describes a tensioning system for use in a retensionable frame used in silk screening wherein the fabric is precut and bordered with splines such that the appropriate tension is predetermined. The Larson patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 6,435,085 B1, issued on Aug. 20, 2002 to James A. York, describes a print screen frame used in the textile screen print industry. The York patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
U.S. Pat. No. 6,561,089 B1, issued on May 13, 2003 to Eugene F. Newman, Jr., describes a screen assembly with border strips already adhered to fabric in precisely measured locations along each edge of the screen fabric. The Newman, Jr. '089 patent does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
Germany Patent Application Publication No. DE 3 533 269 A1, published on Mar. 26, 1987, describes a screen printing frame having a rectangular frame opening bounded by four frame sections for technical and graphic printing. The Germany '269 application does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
Great Britain Patent Application Publication No. GB 2 195 129 A, published on Mar. 30, 1988, describes a screen stretching and securing frame. The Great Britain '129 application does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
Great Britain Patent Application Publication No. GB 2 272 863 A, published on Jun. 1, 1994, describes a screen printing apparatus that includes a screen frame which supports a screen of natural or artificial fabric or metal mesh, a squeegee to force ink through unsealed portions of the screen, and a tunnel supplied with heated air for drying workpieces fed on a transporting belt. The Great Britain '863 application does not suggest a method and apparatus for stretching and mounting a screen printing screen according to the claimed invention.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a method and apparatus for stretching and mounting a screen printing screen solving the aforementioned problems is desired.